BROWNING’S PLATYSCOPIC LENS. 
A NEW ACHROMATIC COMBINATION, 
COMBINING 
WITH THE 
THE DEFINITION OF A MICROSCOPE 
PORTABILITY OF A POCKET LENS. 
The Platyscopic Lens is invaluable to botanists, mineralogists, or entomo- 
logists, as it focusses farther than any other Lens from the objedt, and thus 
.allows opaoue objects to be examined easily* . 
The Platyscopic Lens is made of three degrees of power ; the lowest power 
having the largest field, is the best adapted for general use. 
Price of the Platyscopic Lens , mounted in Tortoiseshell , magnifying either 15, 
20, or 30 diameters , 185. 6 d. 
Illustrated description sent free. 
JOHN BROWNING, 63, Strand, London, W.C. 
NEW AND ENLARGED EDITION. 
Now ready, in crown 8vo., with Frontispiece, price 12s. 
ttEAT a MODE OF MOTION. By John Tyndall, F.R.S., D.C.L. 
H LLD Professor of Natural Philosophy in the Royal Institution of 
Great Britain. Sixth Edition (Thirteenth Thousand), thoroughly revised and 
augmented. London . LONGMANS and CO. 
Tb. -A— cHBFrnrs, 
derate, anil Stieatifu: gOTgfetaan, 
9 , ESSEX STREET, STRAND, W.C. 
As Engraver to this and other Philosophical Periodicals, Mr Cheffins begs 
to call attention to the fad that he possesses every appliance for the Pjoduc 
iLn of Illustrations to the works of Scientific Authors, as well as special 
facilities for the absolutely accurate reproduction of Diagrams, Microscopic 
•Objedts, &c„ by Photography on Wood ; by which process they can be either 
en Elfede 0 nce e d d Dr e a d ughtsmen provided to attend Leaures and Demonstrations, 
and to Sketch Mechanical and other objedts at a f ew hours notice. 
T H E C H EMICAL NEWS 
Edited by WILLIAM CROOKES, F.R.S., &c. 
Published Weekly, price 4 d- Annual Subscription, £i, Payable in advance. 
This Journal is d ev ° te d to Saenti^c ^nd Ap^li^d Cheimst^ai^ a^o^mbr^ces w^ajever 
tends to elucidate new discoveries in Min gy, S contains an encyclopcedic list of 
and the collateral Scie • ^ with abstra as of all susceptible 
SSiSisss £ — 
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